That football leads the list for boys makes sense, but the most dangerous sport for girls, one with catastrophic injuries, is unexpected.

Sports and outdoor play are as important to children and teens as clean air and healthy food, but is there a downside?

Well, yes, unfortunately — kids suffer around 3.5 million sports-related injuries annually in the United States. Although three in four of those injuries are not considered serious, it’s still a daunting figure, especially for the one in four that is serious.

It brings to mind the question: Which sports are responsible for those 3.5 million injuries?

Safe Kids Worldwide commissioned Salter Mitchell to conduct youth sports safety polls among coaches, parents and children in the United States. Perhaps not surprisingly, given its nature, football was the most frequently mentioned sport that caused injuries (39 percent), followed by basketball (16 percent) and soccer (15 percent).

Previous studies have shown that football has nearly twice the injury rate as the next most popular sport, basketball. Research published in the Journal of Athletic Training found that high school football players suffered more than half a million injuries nationwide during the 2005-2006 season; the most common injuries were ligament sprains.

But of greater concern is that high school football players are reported to suffer 43,000 to 67,000 concussions per year — and the true number is likely much higher, as it’s estimated that more than half of players suffering concussions do not report their injury.

Dr. Ann McKee, a Boston University neurological researcher who studies the debilitating disease known as chronic traumatic encephalopathy (CTE), told Time Magazine, in reference to the dangers of football, "We need to do something now, this minute. Too many kids are at risk."

Just because they're not sacking each other with all of their might doesn't mean they're keeping out of harm's way. As for the traditional team sports considered in the Journal of Athletic Training study, soccer was the leading injury producer for the ponytail set — followed by volleyball and basketball — with most of the injuries happening to the lower extremities.

But most disconcerting is what’s happening on the sidelines. According to an eye-opening article in the Los Angeles Times, during the last 26 years, disabilities caused by head or spine injuries are almost twice as high for female high school cheerleaders than for female players of all sports together — to the tune of 73 "catastrophic injuries," and tragically, two deaths.

"Right now, cheerleading is out of control," said Dr. Frederick Mueller, director of the National Center for Catastrophic Sport Injury Research at the University of North Carolina. "Kids are practicing all over the place without mats. They practice when they want to, do what they want to, and some coaches aren't certified and don't know what they're doing."

Cheerleading injuries resulting in emergency room visits have increased almost six times since 1980, to nearly 30,000 in 2008, according to the U.S. Consumer Product Safety Commission.

In most states, high school cheerleading is not considered an official sport, which means it's not mandated to have the same standards of safety equipment, limits on practice time, or training for coaches in the ways other high school sports are required.

But as Mueller points out, “Cheerleading has changed dramatically, from females jumping up and down and shaking pom-poms to a gymnastics-type event where they’re throwing girls 25-30 feet in the air — and sometimes missing them on the way down.”